Since hitting their artistic peak two years ago with Is It Still Good to Ya?, a passionate pop-soul affirmation of a long-lasting erotic love. Nickolas Ashford and Valerie Simpson, the Fred Astaire and Ginger Rogers of black music, have become distressingly formulaic. Indeed, About Love, written and produced by Ashford and Simpson for Gladys Knight and the Pips, tries hard to fit the Pips into a prepackaged concept, and Knight's beautiful, earthy voice has a tough time surmounting the material's Madison Avenue smugness.

Ashford and Simpson's A Musical Affair offers more of the same lushly produced hook-slogans. The album's catchiest songs. "Love Don't Make It Right" and "We'll Meet Again," work mainly because the duo sings them so vivaciously: the chemistry between Simpson's brassy gospel sentimentality and Ashford's husky falsetto can't help squeezing out a few sparks. But except for "Rushing To," the LP's only real departure from empty escapism, the rest of the tunes and arrangements are disappointingly pat.

"Rushing To," a brooding, Curtis Mayfield-style meditation on the desperate pace of modern urban life, suggests that Ashford and Simpson have a lot more to say than "I like happy endings," the idea behind the LP's gooiest number. It's high time these two kicked off their dancing slippers and spoke out. (RS 329)

STEPHEN HOLDEN